Influence of Ag content on microstructure and intermetallic phases of AlSi12 alloy

The main objective of this study is to examine the influence of trace additions of silver on the morphology and composition of the complex microstructure of the intermetallic phases in AlSi12 alloy. Intermetallics were found in short or long rod, or ‘Chinese Script’, forms containing Si, Fe, Mn, Ag and Mg, These compounds became richer towards the grain boundaries. It was observed that the high Ag content intermetallics were created in the form of short rods. In all samples with added Ag, the dendritic structures had transformed into non-dendritic ones. The addition of Ag, in addition to the degeneration of the dendritic structures, enhanced the transformation from rosette form to globular morphologies. The results showed that the amount of eutectic Si increased with small additions of Ag to the AlSi12 alloy. It was established that in general the Ag is distributed within the eutectic structure.